With the advancement of manufacturing ability and increasing consumer demands, flat panel displays, such as Plasma Display Panels (PDP), Organic Light Emitting Diode (OLED) panels, Liquid Crystal Panels (LCP) and Field Emission Displays (FED) and the like, are all being mass produced. The Liquid Crystal Display (LCD) panel has advantages of being thin, light weight, low power consumption, and no radiation contamination. In particular, LCD panels are compatible with semiconductor manufacturing techniques. Therefore, the desktop computers, notebooks, cell phones, Personal Digital Assistants (PDAs), etc., are all using LCD panels as the main display device and are already conventionally being used in daily lifestyle by consumers. However, reducing the weight in LCD panels or other panels is still an important objective.
It is known in the art that LCD panels have been made by using glass as the material of a transparent substrate. Since the weight of a pair of transparent substrates is the main weight of the LCD panel, weight reduction of LCD panels can be achieved by thinning the thickness of the transparent substrates.
The conventional technique for thinning the transparent substrates comprises a grinding/lapping and a polishing, the polishing processes are usually performed by a Chemical Mechanical Polishing (CMP) technique. Implementation method of the CMP technique comprises filling a slurry (e.g. SiO2—AL2O3 and CeO2, etc.) into the gaps of the polishing pad, applying a mechanical force to place the polishing pad onto the surfaces of glass. The slurry in the gaps of the polishing pad contains many chemical scattered abrasives, thereby enabling the glass and the abrasives to react with a fast rotational speed. By doing so, a mechanical cutting force and a chemical reaction are provided to the surfaces of the glass so as to increase the efficiencies of the polishing. In order to significantly reduce the thickness of transparent substrate in this step, it is essential to use large and non-uniform abrasives in polishing the surfaces of the transparent substrate. However, the CMP process is not suitable for LCD thinning. The CMP process only the removing thickness is below 200 nm and the removing rate is below 800 nm/min. Regarding to LCD cell thinning, the removing thickness is from 100 μm to 500 μm and the removing rate is from 3 μm/min to 90 μm/min. For these reasons, we need to grinding/lapping process before polishing process. But it would result in the surfaces of the transparent substrates being extremely rough after the grinding/lapping process.
As described above, the surfaces of the transparent substrates are extremely rough after the grinding/lapping process. In order to avoid increase of error in the following procedure, the transparent substrates with the rough surfaces are not used in the following display panel production procedure. It is necessary to perform a polishing step to the rough surfaces of the transparent substrates after the grinding/lapping process. In the polishing step, planarization of the rough surfaces is done with small and uniform abrasives to further reduce the thickness of the transparent substrates to achieve a predetermined thickness. In prior art, it is necessary to polish both the outer and inner surfaces of the pair of transparent substrates for the display panel until they are smooth and glossy. The polished surface is conventionally known as a mirror surface. Accordingly, other components are able to be disposed on the transparent substrates in following procedures.
However, grinding or lapping a pair of transparent substrates to achieve a predetermined thickness and polishing transparent substrate as the mirror surface take quite a long process time and result in reduction of throughput. For this reason, there is a need to provide a manufacturing method for reducing manufacturing time so as to increase productivity of manufacturing display panels.